BUBBLE REMOVING METHOD FOR CENTRIFUGAL PUMPS

Abstract: A blood delivery port (18) is inclined upward so that a perpendicular line (X) passing the center ( O ) of a centrifugal pump body (12) is positioned between two straight lines (α, β) which connect together two circumferential joint points (A, B) in a joint portion between the blood delivery port (18) and a centrifugal chamber (15) and the centre ( O ), and the centrifugal pump body (12) is supported on a driving unit (13) with a blood take-in port (17) inclined upward at an angle larger than that between an inner circumferential surface of the centrifugal chamber (15) and the axis thereof. After the centrifugal chamber has been filled with a liquid, the driving of a rotary body is done in a low-speed mode, a stopping mode and a high-speed mode in the mentioned order. According to the present invention, the stagnation of bubbles in the centrifugal chamber (15) in the centrifugal pump body (12) at the time of starting the circulation of blood to a circuit such as a pump-oxygenator can be prevented reliably.

Description: Technical Field The present invention relates to a method for eliminating air bubbles in a centrifugal pump which composes an artificial heart-lung machine used to process liquid fluid which includes blood taken from a patient and then return the processed blood and liquid fluid to the patient, during a procedure such as heart surgery. Background Art In general, an artificial heart-lung machine which processes blood as it circulates the blood outside the body is designed to temporarily store in blood storage chamber 1 venous blood taken from a patient's vein via a blood drawing line, as shown in Figure 3. In this design, the blood in this blood storage chamber 1 is relayed via a pump 2 to artificial lung 4 which has a heat exchanger 3. Blood which has undergone gas exchange at the artificial lung 4 is then returned to the patient's artery via a blood return line. Roller pumps, which send out blood by squeezing the tube which forms the blood circulation path with a roller, and centrifugal pumps, which send out blood by means of centrifugal force, may be used as the pump 2 employed in this type of artificial heart-lung machine. An explanation will now be made of the structure of the centrifugal pump using the figures. As shown in Figures 4 and 5, this centrifugal pump 11 is composed of a centrifugal pump main body 12 which sends out the blood which has been taken thereinto, and a driving portion 13 which drives this centrifugal pump main body 12. Vessel 14 which forms centrifugal pump main body 12 has a centrifuge chamber 15, consisting of a conically shaped hollow portion, and a magnet chamber 16 which is sealed off from centrifuge chamber 15. A blood take-in container 17 is formed to this vessel 14 lying along the axis thereof. Further, a blood send-out container 18 is formed to the side of vessel 14 lying in the tangential direction of centrifuge chamber 15 at the side of vessel 14. Further, a shaft 21 which is provided spanning between centrifuge chamber 15 and magnet chamber 16 is supported in a rotatable fashion inside vessel 14. A rotating body 23 which has a plurality of vanes 22,22 is affixed to the end of this shaft 21 .which projects toward centrifugal chamber 15. Further, a circular magnet 24 is affixed to the end of shaft 21 which projects out toward the magnet chamber 16. Further, drive portion 13, which is attached to centrifugal pump main body 12, supports centrifugal pump main body 12 in a state wherein its axis is horizontal and supports blood send-out container 18 in a state wherein it is level above centrifugal pump main body 12 (see Figure 5). A drive magnet 25 which is rotated by means of a motor (not shown) is provided to drive portion 13 in the vicinity of its attachment with centrifugal pump main body 12. By rotating this drive magnet 25 using the motor, magnet 24 of the centrifugal pump main body 12 can be rotated due to the magnet force from drive magnet 25. When magnet 24 of centrifugal pump main body 12 is rotated by drive portion 13, rotating body 23 which has vanes 22,22 rotates. An eddy is generated in the blood within centrifuge chamber 15 by the vanes 22,22. The pressure on the outer periphery inside centrifuge chamber 15 becomes high, while the pressure in the vicinity blood take-in container 17 becomes low. In other words, a pressure difference is generated between the outer periphery of centrifuge chamber 15 and the vicinity of blood take-in container 17. Blood is drawn from blood take-in container 17, and blood in centrifuge chamber 15 is sent out from blood send-out container 18. Vessel 14 of the aforementioned centrifugal pump main body 12 is formed by assembling a funnel shaped body 31 (see Figure 6) which forms centrifuge chamber 15 and a outlet portion 32 (see Figure 7) which forms blood send-out container 18. The inner peripheral surface of centrifuge chamber 15 of the vessel 14 formed in the above described manner must be formed in a tapered shape which progressively widens in the direction moving away from blood take-in container 17 so that funnel shaped body 31 can be withdrawn. For this reason, when circulation of the blood is initiated, as shown in Figure 8, air bubbles sometimes linger at the site indicated by the letter D in the figures between the edge of the inner periphery of centrifuge chamber 15 and blood send-out container 18. Additionally, air bubbles also sometimes lingers at the site indicated by the letter K in Figure 5 which is at a position on a portion of centrifuge chamber 15 which is higher than blood send-out container 18. In this case, as shown in Figure 9, during manufacturing, the side portion of outlet portion 32 may be made to coincide with the tangential line of funnel shaped body 31. However, in so doing, a sharp point must be formed at the area of contact between funnel shaped body 31 and outlet portion 32. This site is very weak, so that it can break or be damaged easily. Further, when attempting to expel the air bubbles which linger at the aforementioned site by force by means of rotating rotating body 23 at high speed, the air bubbles are broken down into smaller air bubbles, becoming attached to the inner surface of the tube which forms the blood circulation path. Accordingly, to eliminate these attached air bubbles requires additional time and trouble. Accordingly, the present invention was conceived out of consideration of the above described circumstances, and has as its objective the provision of a centrifugal pump and an air bubble elimination method where can eliminate air bubbles from lingering in the centrifuge chamber, and can eliminate remaining air bubbles which have become attached to the member elements of the centrifuge chamber. Japanese publication no. JP 405 3565 and EP 0543172 disclose methods of eliminating bubbles from a liquid by driving a centrifugal pump either intermittently or continuously, the nature of the drive being chosen to discharge bubbles from the pump. Disclosure of the Invention According to the present invention, there is provided an air bubble elimination method in a centrifugal pump comprising a drive portion and a centrifugal pump main body connected to the drive portion, wherein said centrifugal pump main body provides a vessel in which is formed a blood take-in container into which blood and liquid filling flows and a blood sent-out container from which the blood and liquid filling is sent out, the inner portion of this vessel forming a centrifuge chamber, a shaft which is rotated by said drive portion inside the vessel, a rotating body which is supported by the end of this shaft, and rotates inside the centrifuge chamber of the vessel, and a plurality of vanes formed on the rotating body which employ centrifugal force on the liquid filling taken in from the blood take-in container by means of the rotation of the rotating body, the centrifuge container having a peripheral wall around the axis of the shaft and tapering inwardly in a direction towards the take-in container; the blood take-in container being formed along the axis of the shaft, and the blood send-out container being formed to extend tangentially from the peripheral wall of the centrifuge chamber, and the inner surface of said centrifugal chamber forming a tapered surface which progressively widens in the direction moving away from the blood take-in container, and the bubble elimination method including: a low speed drive process in which said rotating body is rotated at a low speed by said drive portion thereby lowering the pressure in the vicinity of said blood take-in container; a drive halt process in which the rotation of said rotating body is stopped by said drive portion; and a high speed drive process in which said rotating body is rotated at a high speed by said drive portion; the method being characterised in that: said centrifugal pump main body is supported by said drive portion and has the blood send-out container directed upward so that a vertical line passing through the center point of the centrifugal pump main body is, as seen from the side of the blood take-in container of said centrifugal pump main body, positioned between two straight lines which respectively pass through the center point and two points lying on the circumference of the centrifuge chamber where its periphery connects with the blood send-out container, and the blood take-in container is directed upwardly at an angle from the horizontal which is greater than the angle which is formed between the axis and the taper of the inner peripheral surface of the peripheral wall of the centrifuge chamber; and after the filling liquid fills said centrifugal chamber, the low speed drive process is carried out in which the remaining air bubbles in the centrifugal chamber are moved towards the vicinity of said blood take-in container without breaking the air bubbles into smaller air bubbles; the drive halt process is carried out in which the remaining bubbles which have been moved toward the blood take-in container are moved toward the blood send-out container positioned above the blood take-in container; and then the high speed drive process is carried out in which the remaining air bubbles which have been moved toward the blood send-out container are expelled from said blood send-out container. In this air bubble elimination method, it will be appreciated that a low speed drive process, a drive halt process and a high speed drive process are carried out sequentially. In the low speed drive process, which is intended to move the remaining air bubbles in the centrifuge chamber toward the blood take-in container without breaking the air bubbles into smaller air bubbles, the pressure in the vicinity of the blood take-in container is lowered by rotating the rotating body at low speed by means of the drive portion. In the drive halt process, which is intended to move the remaining air bubbles which have been moved toward the blood take-in container, toward the blood send-out container positioned above, the rotation of the rotating body is halted by the drive portion. In the high speed drive process, which is intended to expel from the blood send-out container, the remaining air bubbles which have been moved toward the blood send-out container, the rotating body is rotated at high speed by the drive portion. As a result, when circulation of the blood is initiated, the remaining air bubbles attached to the inner wall or the like of the centrifugal pump main body can be eliminated easily and with surety, making it possible to greatly reduce the time and labour necessary for the air bubble elimination process at the time of initiation of the use of the centrifugal pump. In the centrifugal pump main body, the blood take-in container is formed along the axis of the shaft, and the blood send-out container is formed at the upper portion of the vessel to the side thereof along the tangential direction. The blood send-out container is directed upward, supported in this state by the drive portion so that the vertical line passing through the center point of the centrifugal pump main body is positioned between two straight lines which respectively link the aforementioned center point and two connection points in the circumferential direction at the site of connection between the blood send-out container and the centrifuge chamber. As a result, the air bubbles in the centrifuge chamber are eliminated naturally as a result of buoyant force. Further, the inner peripheral surface of the centrifuge chamber in this centrifugal pump main body is tapered so as to widen in the direction moving away from the blood take-in container. The blood send-out container is directed upward, supported in this state by the drive portion, at an angle that is larger than the angle formed between the inner peripheral surface of the centrifuge chamber and the axis. As a result, the air bubbles in the centrifuge chamber are eliminated naturally by means of buoyant force. In the low speed drive process, the rotating body of the centrifugal pump main body is preferably rotated at 500 to 1500 rpm. As a result, the remaining air bubbles can be moved toward the blood take-in container without being broken down into smaller air bubbles. Moreover, the duration of the rotation of the rotating body of the centrifugal pump main body in the low speed drive process is preferably 5 to 30 seconds. As a result, the remaining air bubbles can be moved toward the blood take-in container with surety. Further, the duration during which the rotating body of the centrifugal pump main body is halted in the drive halt process is preferably 5 to 30 seconds. As a result, the air bubbles which have accumulated in the vicinity of the blood take-in container can be moved toward the upper end of the centrifuge chamber with surety. Furthermore, the rotating body of the centrifugal pump main body is preferably rotated at 2500 to 5000 rpm during the high speed drive process. As a result, the air bubbles which have been moved to the vicinity of the upper end of the centrifugal chamber can be flushed out from the blood send-out container due to centrifugal force. Moreover, the duration of the rotation of the rotating body of the centrifugal pump main body in the high speed drive process is preferably 10 to 120 seconds. As a result, air bubbles can be flushed out from the blood send-out container with surety. A magnetic body is provided to the shaft in the centrifugal pump main body. The drive portion has a drive magnet which rotates by means of a motor. By rotating the drive magnet using the motor, the magnetic body is attracted to the drive magnet and is rotated. As a result, the rotating body can be rotated in a non-contact state. Moreover, the centrifugal pump of the present invention is comprised of a drive portion and a centrifugal pump main body which is attached to the drive portion. In a centrifugal pump which circulates blood and liquid filling through a path in an artificial heart-lung machine or the like, the centrifugal pump main body is provided with: a vessel wherein there is formed a blood take-in container into which the blood and liquid filling flows and a blood send-out container from which the blood and liquid filling is sent out, the inner portion of this vessel forming the centrifuge chamber; a shaft which is rotated by the drive portion inside the vessel; a rotating body which is supported by the end of the shaft and rotates inside the centrifuge chamber of the vessel; and a plurality of vanes which form the rotating body and employ centrifugal force upon the blood and liquid filling taken in from the blood take-in container by rotating the rotating body. In the centrifugal pump main body, the blood take-in container is formed along the axis of the shaft, and blood send-out container is formed at the upper portion of the vessel to the side thereof along the tangential direction. The drive portion is supported in a state wherein the blood send-out container is directed upward so that a vertical line passing through the center point of the centrifugal pump main body is positioned between two straight lines linking the aforementioned center point and a connection point between two points on the circumference at the connection site between the blood send-out container and the centrifuge chamber. As a result, the air bubbles in the centrifuge chamber are eliminated naturally as a result of buoyant force. Further, the inner peripheral surface of the centrifuge chamber in this centrifugal pump main body is tapered so as to widen in the direction moving away from the blood take-in container. The blood take-in container is directed upward, supported in this state by the drive portion at an angle which is larger than the angle formed between the inner peripheral surface of the centrifuge chamber and the axis. As a result, the air bubbles in the centrifuge chamber are eliminated naturally due to buoyant force. Further, a magnetic body is provided to the shaft in the centrifugal pump main body. The drive portion has a drive magnet which is rotated by means of a motor. By rotating the drive magnet using the motor, the magnetic body is attracted to the drive magnet and is rotated. As a result, the rotating body can be rotated in a non-contact state. A Brief Description of the Figures Figure 1 is a front view of a centrifugal pump provided to explain the centrifugal pump in the embodiment of the present invention. Figure 2 is a side view of a centrifugal pump provided to explain the centrifugal pump in the embodiment of the present invention. Figure 3 is circuit diagram of an artificial heart-lung machine provided to explain the composition of a heart-lung machine. Figure 4 is a cross-sectional diagram of a centrifugal pump provided to explain the structure and construction of a centrifugal pump. Figure 5 is a front view of a centrifugal pump provided to explain the structure and construction of centrifugal pump. Figure 6 is a side view of the funnel of the vessel shown in cross-section provided to explain the funnel which composes the vessel of the centrifugal pump main body. Figure 7 is a plan view of the funnel of the vessel seen in cross-section provided to explain the funnel which composes the vessel of the centrifugal pump main body. Figure 8 is a cross-sectional view of a portion of the centrifugal pump main body provided to explain how air bubbles linger inside the centrifuge chamber of the centrifugal pump main body. Figure 9 is a front view of the funnel of the vessel seen in cross-section provided to explain the funnel of the vessel of the centrifugal pump main body. Preferred Embodiments of the Present Invention Preferred embodiments of the air bubble elimination method in a centrifugal pump according to the present invention will be explained below with reference to the figures. Additionally, it is noted here that where structural parts are identical to those in the centrifugal pump described above, the same numeric symbol will be employed and an explanation will be omitted. As shown in Figures 1 and 2, in the centrifugal pump 41 of the present embodiment, the centrifugal main body 12 is connected to drive portion 13 as follows. As shown in Figure 1, in this centrifugal pump main body 12, blood send-out container 18 is directed upward and supported in this state, so that a vertical line X passing through the center point O of centrifugal pump main body 12, as seen from the side of the take-in container 17 of said centrifugal pump main body 12, is positioned between two straight lines α, β which respectively pass through center point O and a point A and center point O and a point B, points A and B lying on the circumference of centrifugal chamber 15 where its periphery connect with blood send-out container 18. Further, Further, as shown in Figure 2, in centrifugal pump main body 12, blood take-in container 17 is directed upward and supported in this state with a tilt angle δ which is larger with respect to horizontal line Z than the tilt angle γ which is formed between axis Y and the tapered inner peripheral surface of centrifuge chamber 15. In other words, in this centrifugal pump 41, because centrifugal pump main body 12 is supported in a state wherein it is tilted as described above, it is possible to obtain a centrifugal pump with a centrifuge chamber 15 which does not have an area in which air bubbles linger (i.e., an area such as that indicated by D in Figure 8 and K in Figure 5), as occurred in the conventional art. Accordingly, when forcing the blood and liquid filling to flow into the centrifuge chamber 15 from the tube, (not shown in the figures) which is to circulate the blood in the circulation path of the artificial heart-lung machine and which is connected to blood take-in container 17 of centrifugal pump main body 12, and then flow out from blood send-out container 18 to the tube (not shown in the figures) connected to blood send-out container 18, air bubbles do not linger within centrifugal pump main body 12 but are expelled from blood send-out container 18 in the blood and liquid filling. However, air bubbles may become attached and remain to recessed contoured areas such as the vanes 22,22. In these cases, it is necessary to remove the attached air bubbles. In order to do so, in the present embodiment, centrifugal pump 41 is driven in the following way to carry out the elimination of remaining air bubbles when circulation of the blood and liquid filling is initiated. (1) The motor of drive portion 13 is operated at low speed (500 to 1500 rpm), rotating at low speed drive magnet 25 of drive portion 13. In so doing, drive magnet 25 of drive portion 13 is also rotated, rotating magnet 24 of centrifugal pump main body 12. Accompanying this, rotating body 23 rotates.As a result, an eddy is generated by vanes 22,22 in the blood and liquid filling inside the centrifuge chamber 15, giving rise to a pressure difference in the blood and liquid filling inside centrifuge chamber 15.In other words, the pressure at the outer peripheral side in centrifuge chamber 15 becomes large, while the pressure around the vicinity of blood take-in container 17 becomes small.Accordingly, the air bubbles which remained inside centrifuge chamber 15 move toward blood take-in container 17 which is at low pressure.Because rotating body 23 is rotating at low speed at this time, the remaining air bubbles within centrifuge chamber 15 do not break up into smaller air bubbles, but move toward blood take-in container 17.Additionally, it is noted here that the duration of this low speed rotation is of a time length (5 to 30 seconds) sufficient for the remaining air bubbles to move toward blood take-in container 17. (2) Next, by halting the motor of the drive portion 13, the rotation of rotating body 23 is halted. In so doing, the pressure difference at the centrifuge chamber 15 is eliminated, the air bubbles which moved to blood take-in container 17 in process (1) above move toward the upper end of the centrifuge chamber 15 due to buoyant force.Additionally, it is noted here that the duration during which the motor of drive portion 13 is halted is of a time length (5 to 30 seconds) which is sufficient for the aforementioned air bubbles to move toward the upper end of centrifuge chamber 15. (3) Then, the motor of drive portion 13 is again rotated to rotate rotating body 23 of centrifugal pump main body 12 at high speed (2500 to 5000 rpm) for a fixed period of time (10 to 120 seconds). In so doing, as in (1) above, a pressure difference is generated in centrifuge chamber 15. However, because the rotation is carried out at high speed, and the air bubbles which moved to the area around the upper end of centrifuge chamber 15 are flushed out from blood send-out container 18 to the tube along with the blood and liquid filling as a result of centrifugal force. By carrying out operations (1) through (3), the air bubbles which remained in centrifuge chamber 15 can be expelled with ease and surety from blood send-out container 18, and centrifuge chamber 15 of centrifugal pump main body 12 can be filled with the blood and liquid filling. After filling the circulation path with the blood and liquid filling, centrifugal pump 41 is driven at an ordinary number of rotations (1500 to 3000 rpm), carrying out circulation of the blood outside the patient's body. In this way, by means of the centrifugal pump and air bubble elimination method of the above described embodiment, it is possible to eliminate air bubbles lingering at sites which have a shape conducive to causing this phenomenon and to greatly improve the safety of the artificial heart-lung machine. Further, it is possible to eliminate with extreme ease and surety the air bubbles which remained in centrifugal pump main body 12 at the time of initiation of circulation of the blood. In other words, the time and labor required for air bubble elimination operations when initiating use of centrifugal pump 41 can be greatly reduced. Additionally, it is noted here that the above described preferred embodiment of the present invention used the situation where the centrifugal pump 41 is provided in the middle of the circulation path of the artificial heart-lung machine as an illustrative example. However, centrifugal pump 41 is not limited to the path of the artificial heart-lung machine, but may be suitably employed anywhere in the circulation path. Further, when eliminating air bubbles in centrifuge chamber 15 of centrifugal pump main body 12, the duration during which drive portion 13 is driven, the duration during which driving is halted, the rotating speed and the like are not limited to the preferred embodiments, but may of course be suitably changed in accordance with the size or the like of the centrifugal pump main body 12. Furthermore, in the above described preferred embodiment, a construction wherein magnet 24 of centrifugal pump main body 12 is rotated by the magnetic force of drive magnet 25 which rotates at the drive portion 13 side was employed as the means for rotating rotating body 23 in centrifugal pump main body 12. However, the means for rotating rotating body 23 inside centrifugal pump main body 12 is not limited to the above described embodiment. Furthermore, provided that it is a magnetic body which is attracted by the magnetic force of drive magnet 25, the magnet used for magnet 24 of centrifugal pump main body 12 is not particularly restricted. Industrial Field of Application As described above, the air bubble elimination method in a centrifugal pump according to the present invention allows air bubbles remaining in the centrifugal pump main body to be eliminated with extreme ease and surety at the time of initiation of circulation of the blood. Namely, the present invention is appropriately employed to greatly reduce the time and labor of air bubble elimination operations at the time of initiation of use of a centrifugal pump.

Claims: An air bubble elimination method in a centrifugal pump (41) comprising a drive portion (13) and a centrifugal pump main body (12) connected to the drive portion (13), wherein said centrifugal pump main body (12) provides a vessel (14) in which is formed a blood take-in container (17) into which blood and liquid filling flows and a blood sent-out container (18) from which the blood and liquid filling is sent out, the inner portion of this vessel (14) forming a centrifuge chamber (15), a shaft (21) which is rotated by said drive portion (13) inside the vessel (14), a rotating body (23) which is supported by the end of this shaft (21), and rotates inside the centrifuge chamber (15) of the vessel (14), and a plurality of vanes (22) formed on the rotating body (23) which employ centrifugal force on the liquid filling taken in from the blood take-in container (17) by means of the rotation of the rotating body (23), the centrifuge container (15) having a peripheral wall around the axis of the shaft and tapering inwardly in a direction towards the take-in container (17) ; the blood take-in container (17) being formed along the axis of the shaft (21), and the blood send-out container (18) being formed to extend tangentially from the peripheral wall of the centrifuge chamber (15), and the inner surface of said centrifugal chamber (15) forming a tapered surface which progressively widens in a direction moving away from the blood take-in container (17), and the bubble elimination method including: a low speed drive process in which said rotating body (23) is rotated at a low speed by said drive portion (13) thereby lowering the pressure in the vicinity of said blood take-in container (17); a drive halt process in which the rotation of said rotating body (23) is stopped by said drive portion (13); and a high speed drive process in which said rotating body (23) is rotated at a high speed by said drive portion (13); the method being characterised in that : said centrifugal pump main body (12) is supported by said drive portion (13) and has the blood send-out container (18) directed upward so that a vertical line (X) passing through the centre point (0) of the centrifugal pump main body (12) is, as seen from the side of the blood take-in container (17) of said centrifugal pump main body (12), positioned between two straight lines (α,β) which respectively pass through the center point (0) and two points (A,B) lying on the circumference of the centrifuge chamber (15) where its periphery connects with the blood send-out container (18), and the blood take-in container (17) is directed upwardly at an angle (δ) from the horizontal which is greater than the angle (γ) which is formed between the axis (Y) and the taper of the inner peripheral surface of the peripheral wall of the centrifuge chamber (15); and after the filling liquid fills said centrifugal chamber (15), the low speed drive process is carried out in which the remaining air bubbles in the centrifugal chamber (15) are moved towards the vicinity of said blood take-in container (17) without breaking the air bubbles into smaller air bubbles; the drive halt process is carried out in which the remaining bubbles which have been moved towards the blood take-in container (17) are moved towards the blood send-out container (18) positioned above the blood take-in container (17); and then the high speed drive process is carried out in which the remaining air bubbles which have been moved towards the blood send-out container (18) are expelled from said blood send-out container (18). An air bubble elimination method according to claim 1 in which the rotating body (23) of the centrifugal pump main body (12) is rotated at 500 to 1500 rpm during the low speed drive process. An air bubble elimination method according to claim 1 or claim 2 in which the duration of rotation of the rotating body (23) of the centrifugal pump main body (12) during the low speed drive process is 5 to 30 seconds. An air bubble elimination method according to any one of claims 1 to 3 in which the duration during which the rotating body (23) of the centrifugal pump main body (12) is halted during the drive halt process is 5 to 30 seconds. An air bubble elimination method according to any one of claims 1 to 4 in which the rotating body (23) of the centrifugal pump main body (12) is rotated at 2500 to 5000 rpm during the high speed drive process. An air bubble elimination method according to any one of claims 1 to 5 in which the duration of rotation of the rotating body (23) of the centrifugal pump main body (12) during the high speed drive process is 10 to 120 seconds. An air bubble elimination method according to any one of claims 1 to 6 in which a magnetic body (24) is provided on the shaft (21) and a drive magnet (25) which is rotated by a motor is provided on the drive portion (13), the magnetic body (24) being attracted by the drive magnet (25) and rotated as a result of the rotation of the drive magnet (25) by the motor.

Inventors: AIZAWA TAKESHI, ISHII SHUICHI, ITO KAZUYUKI, KUWANA KATSUYUKI, MATSUURA MOTONORI, AIZAWA, TAKESHI, ISHII, SHUICHI, ITO, KAZUYUKI, KUWANA, KATSUYUKI, MATSUURA, MOTONORI, AIZAWA, TAKESHI NIKKISO CO. LTD., ISHII, SHUICHI SENKO MED. INSTR. MFG. CO. LTD., ITO, KAZUYUKI NIKKISO CO. LTD., KUWANA, KATSUYUKI SENKO MED. INSTR. MFG. CO.LTD., MATSUURA, MOTONORI NIKKISO CO. LTD.
Applicants: NIKKISO CO LTD, SENKO MED INSTR MFG, NIKKISO CO., LTD., SENKO MEDICAL INSTRUMENT MFG. CO., LTD.
Application year: 1994
Main classification: A61M1
IPC codes: A61M1